The invention relates generally to the field of ophthalmic apparatuses and more particularly to a two position ophthalmic apparatus wherein the positions are determined by rotation about a longitudinal axis.
Eye testing is performed on a regular basis for patients of various ages to evaluate vision and to check for the presence of eye diseases such as, without limitation, cataracts, glaucoma, macular degeneration and diabetic retinopathy. One test often performed is a visual field test which evaluates whether the patient has difficulty seeing in any areas of their peripheral vision.
Perimetry is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of test targets on a defined background. Perimetry can be clinically performed with confrontational field testing, in which the patient's gaze is held fixed on a target, while objects are presented at various places in the visual field. Inputs received by the patient responsive to the presented objects are used to automatically map and quantify the visual field testing.
Static perimetry involves the presentation of repeated stimuli at increasing levels of intensity until the stimulus is detected by the patient. Kinetic perimetry involves the presentation of a moving stimulus of a particular size and intensity. The stimulus is moved from an area outside of the visual field towards the fixation target until it is detected by the user.
Perimetry typically requires independent testing of each eye, because images perceived by the other eye may affect the results of the tested eye, and a record of the test must be associated with the eye being tested. Thus, the perimetry device must provide a means for selecting the eye to be tested, a means for occluding the non-selected eye, and a means for coordinating the testing and the results with the selection of the eye to be tested. Similarly other eye tests, such as tests for visual acuity and contrast sensitivity, are best accomplished with a means for selecting the eye to be tested, a means for occluding the non-selected eye, and a means for coordinating the testing and the results with the selection of the eye to be tested.
U.S. Pat. No. 6,656,131 issued Dec. 2, 2003 to Alster et al, U.S. Pat. No. 7,275,830 issued Oct. 2, 2007 to Alster et al, and U.S. Patent Application Publication S/N 2007/0121070 A1 published May 31, 2007 to Alster et al, the entire contents of each of which are incorporated herein by reference, are addressed to methods and systems for detecting eye disease. Such perimetry devices are designed for use by qualified personnel and as such result in infrequent use by any particular patient. Generally, the requirement to visit a physician to perform a test results in infrequent testing due to the added cost and inconvenience of arranging such a test with a physician.
Certain diseases of the eye may progress rapidly, and frequent follow up is thus desirable. As indicated above, testing by a physician, or other qualified personnel, results in reduced frequency of testing. It is to be noted that the need for frequent follow up is often a function of the age of the patient. Unfortunately, as patients age their ability to learn, and/or handle, sophisticated equipment, often declines. Thus it would be desirable to provide an eye testing apparatus which can be used by the patient without the intervention of qualified personnel.
Vision therapy devices, including without limitation eye training and eye exercise devices are known in the art. Such vision therapy devices are utilized by a patient, or a user, to improve or stabilize an eye condition, in particular without limitation one of low vision, amblyopia, myopia and strabismus. Such vision therapy devices would be positively impacted by the existence of a dual position ophthalmic apparatus designed for use by a patient without intervention of qualified personnel.
The terms patient and user, as used throughout this document, are used interchangeably and are meant to be directed to the subject having the eye being tested or for whom the vision therapy is directed.
What is needed is a simple low cost eye testing or eye therapy device, generally termed an ophthalmic apparatus, which is operable by a user without requiring qualified trained personnel.